Alpine flowers could go extinct after glaciers disappear as more competitive species colonise terrain higher up the mountain, new research has warned.
Glaciers are retreating at historically unprecedented rates, exposing new land for plants to grow, which benefits delicate alpine species in the short term. However, these early pioneers – some of which are endemic – soon become endangered as more aggressive species take over, driving them out of their remaining habitat and decreasing overall biodiversity, according to the paper published in Frontiers in Ecology and Evolution.
Up to 22% of species studied on four glaciers in the Italian Alps would disappear from the area once the glaciers have gone, the researchers found. Endemic plants such as mossy saxifrage, purple mountain saxifrage and mignonette-leaved bitter-cress would probably become extinct 150 years after the glaciers disappeared, according to lead researcher Dr Gianalberto Losapio, an ecologist from Stanford University.
Proglacial environments are highly sensitive to global warming, and mountain species are subject to the “escalator to extinction”. They need to move to a higher-altitude habitat as the climate warms, but there is no more space for them to do this. “I think we can be relatively confident that our results can be extended to elsewhere in the Alps and other mountain ecosystems, like the Himalayas, the Karakoram and the Andes,” Losapio said.
Researchers found the retreat of glaciers affected 51% of species – 29% of species would flourish while 22% could face local extinction. Rarer, specialist species that have adapted to grow in the harshest conditions (for example by growing close to the ground so they don’t get blown away) colonise areas less than 100 years after the glacier melts. After 150 years, competition becomes fiercer, and more generalist species such as alpine sedge, alpine meadow-grass and dwarf yellow cinquefoil have the upper hand.
Alpine plants are a key part of fragile mountain ecosystems so their disappearance is likely to lead to other local extinctions, said Losapio. “They are the primary producers … they are not only our food but fuel for all of the ecosystem – the consumers, predators, parasites, herbivores and pollinators.”
Researchers used geological records to reconstruct glaciers so they could work out when ice retreated from different parts of the mountain. This information was combined with a survey of 117 plant species observed in hundreds of plots up to 50m2 in size, alongside analysis of local environmental conditions.
They studied the Vedretta d’Amola glacier, the Western Trobio glacier, Rutor glacier and Vedretta di Cedec glacier. By combining datasets, researchers could examine changes over the past 5,000 years and make predictions for the future.
In terms of what the Italian Alps will look like in 100 years, it depends on what happens to precipitation, and there is no consensus on this. “Like the boreal forest in Scandinavia or Canada, if it rains a lot it could be a continuous forest, with wet, humid, deep productive soil. If it doesn’t, it will look more like the Sierra Nevada in Spain or California,” said Losapio.
Research from the University of Zurich has previously shown that alpine plants are not keeping up with climate change, with invasive species colonising the tops of mountains faster. Botanists working in the Highlands of Scotland also found Britain’s rarest mountain plants were retreating higher and being replaced by grasses normally found at lower altitudes.
As well as working to reduce emissions, educating people and raising awareness about fragile mountain ecosystems could help protect these environments, according to Losapio. Encouraging people to stick to paths and not build additional ski slopes would also help.
Dr Trevor Dines, a botanical specialist at British charity Plantlife, who was not involved in the research, said: “Our native mountain flora is highly vulnerable; 44% of montane species are under threat of extinction – a higher proportion than any other habitat.
“Rock faces that are home to fragile flowers such as tufted saxifrage, mountain avens and moss campion are now choked with grasses, mosses and rushes as the fertility of the thin soil increases. Together, the parallel threats of climate change and nitrogen deposition could create a perfect storm for our delicate mountain flowers.”
Ian Dunn, the chief executive of Plantlife, said: “This report is invaluable as the forecasting allows conservationists to better predict the changes afoot. They do not look positive. We must work together to meet the challenge of both climate change and biodiversity loss and Plantlife is looking for the UN’s Convention on Biological Diversity Post-2020 Global Biodiversity Framework to clearly address the conservation of wild plants and fungi.”
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